In recent years, even in an ordinary home, digital apparatuses such as a D-VTR (Digital Video Tape Recorder) for recording digital broadcast and the like are being spread. In association with it, the operation such that the digital broadcast is received and outputted to a television receiver and the digital broadcast is monitored or the operation such that the digital broadcast is transferred to the D-VTR and recorded as a digital signal as it is can be easily performed.
For example, the IEEE (The Institute of Electrical and Electronics Engineers) 1394 serial bus having a high degree of freedom of connection and high durability is used for mutual connection of the digital apparatuses.
According to the IEEE1394 serial bus, even when a power source of the electronic apparatus connected thereto is in a standby mode, the power source of the electronic apparatus can be turned on by sending a command. Each electronic apparatus, therefore, is set to the standby mode and a current is always supplied to the apparatus.
However, when the power source of the electronic apparatus is OFF (disconnecting state), since no command can be received, the existence of the electronic apparatus cannot be recognized. Further, there is a problem such that when the number of electronic apparatuses connected to a network increases, it is difficult to distinguish the electronic apparatus in the standby mode including a power-on state from the electronic apparatus in the disconnecting state.
Therefore, although there is a method of always setting the power sources of all of the electronic apparatuses connected to the network into the standby mode, an electric power is supplied even to the electronic apparatus whose use frequency is low, so that there is a problem such that a large electric power (standby electric power) is eventually consumed.
There is also a problem such that since the IEEE1394 serial bus communicates with many apparatuses, in the apparatuses connected to the bus, it is necessary to make many circuits operative and, since the apparatus operates at a high speed, a large electric power (standby electric power) is consumed even in the standby mode.